Hacksaw



21, 1937. G'. 1. BLUM 2,102,782

HACKSAW Filed Feb. 2, 1934 Patented Dec. Z1, 1937 2,102,782 HAcKsAW film of Illinois Application February '2, 1532i, .Serial-"Nd '109,117

. 6 Claims.

The invention pertainsto hack saws, and in certain of its aspects relates particularly to hand saws.

One obiect of the invention is to provide anim- :5 proved blade holderrfor hack saws, such that the endsof the blade may be held rigidly against torsional strains.

.Another Objectis toprovide a blade holder for hack saws whichi's capable of clamping the ends of 'the` blade rigidly inr position, and which is susceptible of convenient operation in inserting and removing blades.

Still another vobject `is to provide an improved form of blade clamping mechanism adapted to utilize thetensionin, the blade for moving the .mechanism into tight clamping engagement with the associated end portion of the saw blade.

v A further object is to provide a hand hack saw having blade holders mounted in the 4ends of a U-shaped frame `and handles associated with the opposite blade holder arranged to permit of a more direct-application-of the reciprocating force tothe blade.

The objects of the invention thus generally a stated together with otherand .ancillary advantages are obtained in the accompanying drawing forming a part hereof whereinz- Figure 1 is a side elevational view of a hack saw embodying my invention.

Fig. 2 is a similar view illustrating the blade in adiierent relation, but showing the frame inclined with respect to the line of cut.

Fig. 3 is the longitudinal sectional view on an enlarged scale taken approximately in the pla-ne of line 3-3 of Fig. 1, and illustrating the details of construction of my improvedblade holders.

Fig. 4 is a fragmentary rsectional view showing fthe bladeclamp ofthe `holder with its movable clamping jaw in open position.

Fig. 5 is an exploded View of the blade-holding clamp with the parts in position for-assembly.

Inthe embodiment of my invention selected for purposes of illustration, l designates a rigid U- shaped frame preferably of cast metal having front and rear arms '8 and 9 in the 'free ends of which are mounted blade holders generally designated IE! and II., in which the opposite .ends of a hack saw blade I2 are clamped. Associated with the respective blade holders I0 and I I are rear and forward handles vI2 and I3.

The present invention contemplatestensioning means for the blade andanimproved arrangement for one or both ofthe blade holders including a stem membe1' ;posi tvely connectedwith the respective-arms 8 or 9 and having a f lxedly secured bladeanchoring element tohld the vblade 'against longitudinal movement relatveto the stern meinber while the blade is under tension. Moreover, the invention provides clamping means 'on the holder operative as an incident to anlin'crease in tension on the blade to grip the blade withincreasing pressure.

c As shown in Fig. V3, "the blade holder 'III coinprises a stem 'III Vherein `shown as cylindrical in form. and slidablethrough "afho'le I5 in a headed endpertion I o'f 4the frame v8'. At theinr'er eid o f this stem is a blade clamp having a xed jaw I8 and amovable jaw I1.

As herein shown, the two jaws I1 and I8 are substantially semi-circular in cross vsectifcn and respectively provide fflat clamping .surfaces "I8" and I9. In mounting the mvablejaw for"mvevment relative to the xed 'jaw va 'pivotal 'con'- nection is employed, and "for this purpose, the movable jaw 'has -formed integral 'therewith 'an annulus 20 loosely encircling Lthe 'stein I`4. jawproper is offset to vone side o`f lthe axis ofthe annulus for cooperation with the Stationary 'jaw I-8, which is similarly o'lst't de's'ide f the -sterili 'I"4,.'bt`n adirctn 'opposite the'rnovabljaw IL In .the movable jaw isi'r'lounteda blade-anchoring element in the foii Of a. pin 2l p'ijedtng from the clampingfac'e I9 'and adapted to'enter a'recess '.2`2'infthe stati'na'ryf j 'aw in theclairip'ed relation' df parts. over tmspin as snow'njin Fig. eine y enga .of the blade 'is inserted, the latter beingfpr; Vi'dfvvtlflth ,US'al hole 23 for thispulp'ds.

In rnaliihg the blade clamps, I employ 'a "cn.- .struction .permitting of veryecoiiomi'caI malnuactre. Thus, the stationary jaw I8 is formed integral with Athe stern I4 by milling the "in'n'el" end .of the stem transversely t'o a depth slightly beyond the axis 'f the stein, fthus 'making this jaw substantially 'semi-circular in cross section.

The movable j aw I'I ahd'its-supporting'annuls I A2l) are Similarly fol'nled 'from round Inetal Stock. In this operation, a short piece 'of such'stock boredaizially thereof at one end 'to form 'the aiinlilus 2'0, and the yother 'eid 'is I'Iiilled 'trallSf versely s'o as 'to form the 'jaw AI"I. The width of the cut is such as to intersectat ne e-nd'tlier inner .end of the boie made informing the "ainnulus. 'I'hus, a segmental peni'n'g 2'IIv is formed at the inner end of the lan'nulus and 'at one'side of the jaw I-'I for receiving the xed jaw I8. "The annlus isi'nade of a 'diameter such afs 'to fit Vloosely over .thefstem I4.. 4and "to perini'tff a pivotal movement, Of the jaw I1, the ariiulus 4is citerbored at an aiigle'tb its aids 'so 'ast eilt away the pagina ef the en mesme .5 5

` carrying the jaw Il, as indicated at 25, and also to remove a portion of metal at the opposite side ofthe annulus, as indicated at 25.

In mounting the movable jaw pivotally on the stem I4, I employ a hardened radial pin 26 pressed into the stem and projecting a short distance beyond the surface on the side of the stationary jaw IB. This pin is entered through a hole 2'1 in the corresponding side of the annulus, the hole being of such size and shape as to permit of the rocking of the annulus relative to theV stem and thereby of a limited pivotal movement of the jaw I'I relative to the jaw I8. i

It will be observed that the pivot point of. the movable jaw is offset laterally from the point of connection with the blade. Accordingly, with the latter hooked over its pin, an endwise force exerted on the stem in a direction-away from the blade will cause the movable jaw to swing toward the stationary jaw, and the greater such end-v wise force, the greater will be the ensuing clamping action, it being assumed, of course, that the blade is held stationary at its opposite end.

The clamp II for the rear end of the blade is of the same construction as the clamp l and need not, therefore, be described in detail. In this instance, the xed jaw is formed integral with a stem 28' extending slidably through a head 28 at the lower end of the frame arm 9, and carried by the stem is a radially projecting pin 29 adapted to bearV at oppositely projecting ends against the rear face of the head 28. Rearwardly ofthe pin 29 the rear handle I2 is secured to the stem 28. As herein shown, this handle is in the form of. a casting projecting downwardly and rearwardly from the stem and shaped to be gripped conveniently by the hand of the operator. The forward handle I3 is also in the form of a casting and is mounted on the forward end of the stem I4 so as to project upwardly therefrom in spaced relation to the front frame arm 8. This handle has as an integral part thereof a nut 30 in screw threadedV engagement withV the stem I4 and, adapted to bear against the forward face of the head I6. of the arm 8 to draw the same forwardly and ,thereby tighten the blade in the clamps I0 and II. `For the purpose of. holding `the parts in adjusted relation, the nut 30 and head I6 are corrugated to provide coacting cam faces, as indicated at 3| (Fig. 1). Thus, when the blade is placed under tension a yieldable frictional resistance is interposed sufficient to hold the nut against rotation. y

In order that the blade may be secured in any one of a plurality of positions angularly relative to the frame, each of the stems I4 and 21 is adapted tobe secured in different angular positions in their respective headsV I6 Vand 28. Thus, the stem I4 is provided with a radial ypin 32 `(Fig. 3) engageable with one of a plurality of longitudinalgrooves 33 cut in the wall of the bore I through thehead. Herein, the grooves are employed .spaced circumferentially 90 degrees apart. Similarly, at the rear end of the saw, the opposite ends of the pinv 29 on the 'stem 28 are adapted to engage in radial grooves 34 cut in therear face of the head 28, four such grooves, spaced 90 Vdegrees apart, being preferably employed.

From a comparison of Figs. 1 and Y2, it will be apparent that by the construction set forth, the

blade I2 may be clamped in any one of three different angular positions relative to the frame. Thus, the blade may be clamped in either of two angular positionsspaced 90 from that shown in Fig. 1, so that when the bladeis disposed in a;

vertical plane, the frame may be Vtilted to one side or the other as shown in Fig. 2.

It will be seen that I have provided a hack saw of a very practical character, having clamps of simple construction capable of holding thev blade effectively against torsionalV strains and thereby eliminating all danger of disengagement of the blade from its anchoring means, as well as substantially reducing the possibility of breakage of the blade. Moreover, by the provision of front and rear handles mounted directly on the blade holding stems, the reciprocating force may be applied to the saw blade directly along the line of the Vcut being made. Finally, the construction of the blade clamps is such as to permit of easy attachment and removal of the blade.

I claim as my invention:

1. A blade holder for hack saws comprising an endwise movable member, a xed jaw rigid with said member, a movable jaw, one of said jaws having a disengageable connection with the end of a saw blade, a pivotal connection between said jaws in laterally offset relation to said connection with the blade and on the side of said member away from the clamping face of said fixed jaw, said movable jaw being adapted to rock in the direction of the xed jaw as an incident to an increase in tension on the'table.

2. A blade holder 'for hack saws, comprising a stem having a xed clamping jaw rigid there-1 with with a flat clamping face disposed substan-u. tially on the longitudinal center line of the stem, a movable clamping jaw in opposed Vrelation tol the fixed jaw, a blade-anchoring element carried by said movable `jaw, and a supporting member for the movable jaw pivoted on the stem on the opposite side of said center linefrom the movable jaw.

3. A blade holder for hack saws, comprising a stem having a xed clamping jaw rigid therewith with a iiat clamping face disposed substantially on the longitudinal center line of the stem, a movable clamping jaw in opposed relation to the xed jaw, a blade-anchoring element carried by said movable jaw, and an annulus loosely encircling said stem and carrying saidV movable jaw, said annulus having a pivotal connection with the stem on the side thereof opposite the movable jaw.

4. A blade holder for hack saws, comprising a cylindrical stem having one end portion cut to form a xed clamping jaw on one side thereof with a flat clamping face disposed in substantial alinement with the axis of the stem, an annulus loosely encircling-the stem, a pivot pin carried by the stem on the side carrying the xed jaw, said annulus having an aperture loosely receiving said pinV and being adapted to rock relative to the stem, a movable clamping jaw rigid with said annulus and having a flat clamping face movable in the rocking movement of the annulus toward and from the clamping face of the fixed jaw, andan anchoring stud on said movable jaw adapted to receive the apertured end of a saw blade.

' V5. A hack saw comprising a frame having front and rear arms, anchoring means for one end of the blade carried by one of said arms, a clamp on the other arm having opposed jaws and an anchoring element for the blade, and means for placingthe blade under tension, one of said jaws being swingable to carry the same toward and away fromthe other jaw at one side of the blade and having a pivotal support on the other side of the blade operative as an incident to an increase in the tension on the blade to cause said jaws to grip the same with increasing pressure to prevent sidewise movement thereof, said anchoring element serving positively to maintain the blade against longitudinal movement relative to the clamp.

6. A blade holder for hack saws comprising, in combination, an elongated member adapted to be mounted in a saw frame, a xed clamping jaw rigid with one end of said member and disposed at one side of the axis thereof, a movable clamping jaw adapted for coaction with the fixed jaw for the reception therebetween of a saw blade, a support for the movable jaw extending transversely of said member and having a pivotal connection therewith at the side thereof carrying said fixed jaw and on the opposite side of the xed jaw from the movable jaw, and an anchoring element cooperating with said jaws to hold the blade against movement relative thereto.

GEORGE J. BLUM. 

